Consider the TIME fixed effects model Y subscript i t end subscript equals b X subscript i t end subscript plus c subscript i plus u subscript i t end subscript comma space space i equals $1$ comma horizontal ellipsis comma n comma space space t equals $1$ comma horizontal ellipsis comma T comma $($a$)$ What is the INTERCEPT for: $($i$)$ entity $1$ in time period $1$; $($ii$)$ entity $1$ in time period $2$; $($iii$)$ entity $2$ in time period $1$; $($iv$)$ entity $2$ in time period $2?($b$)$ The same model can also be written as: Y subscript i t end subscript equals a plus b X subscript i t end subscript plus d subscript $2$ D $2$ subscript i t end subscript plus horizontal ellipsis plus d subscript T D n subscript i t end subscript plus u subscript i t end subscript comma space space i equals $1$ comma horizontal ellipsis comma n comma space space t equals $1$ comma horizontal ellipsis comma T comma where D $2$ subscript i t end subscript equals $1$ if i $=2$ and $0$ otherwise, D $3$ subscript i t end subscript equals $1$ if i $=3$ and $0$ otherwise, and so forth. Express the following coefficients in terms of the coefficients left parenthesis c subscript $1$ comma c subscript $2$ comma horizontal ellipsis comma c subscript n right parenthesis: $($i$)$ a $($ii$)$ d subscript $2$